Electric rivet heater



Jan. 14, 1930. F, P, @BERT 1,743,609

ELECTRIC. RIVET HEATER Filed Sept. 22. 1921 .5 Sheets-Sheet 1 El 4 W JNVENTOR ATTQREYJ 1930- F. P. KOBERTY 97439609 ELEC'IRI C RIJET HEATER Filed Sept. 22. 1921 3 Sheets-Sheet 2 Jan. 14 1930; F; P. KOBERT ELECTRIC RIVET HEATER Filed Sept 22. 1921 a Sheets-Sheet a W 5/ ATiOZjZ Patented Jan. 14, 1936 ELECTRIC RIVIEE'I. H'IEE Application filed September 22, 1921. Serial No. 502,866.

The present invention relates'to methods and means for heating metal objects, such as rivets, electrically to a forgin or other desired temperature. It is an ob ect of the 6 present invention to devise methods and means of the character specified which will be extremely simple in operation, which will enable the heating of the desired objects, such as rivets, to take place at greater speeds and with less consumption current and with less danger of burning or otherwise deleteriously affecting the metal objects, such as rivets, than has hitherto been possible. It is a further object of the present invention to devise apparatus for thepurpose specified which will be less cumbersome and less expensive than the apparatus hitherto employed for the same purpose while at the same time having a much greater capacity and carrying out the desired heating operation more economically and efiiciently.

By Way of example, there is, in the accompanying drawings and specification, shown and described an illustrative embodiment of the apparatus of the invention in which an illustrative embodiment of the process of my invention may be carried out successfully. It is, however, to be clearly understood that the illustrative embodiments of the apparatus and process of my invention herein shown and described are so shown and described for purposes of illustration only.

Referring to the drawings in which the aforesaid illustrative embodiment of the apparatus of my invention is illustrated,

Figure 1 shows a side elevation;

Figure 2 shows a top elevation;

Figure 3 shows a horizontal section of the aforesaid embodiment of the apparatus of my invention taken along the line of 33 of Figure 1, certain parts being shown in elevation; while Figure 4 is a detail elevational view of a portion of the machine.

Before describing in detail the aforesaid illustrative embodiments of the apparatus and process of my invention it may be desirable briefly to point out the defects of the deviceshitherto used in the art for accomplishing the same general purpose, namely to heat metal objects, such as rivets, to a forging or other desired temperature. The rivet heaters, for example, hitherto employed, have required for the attainment of the desired degree of temperature the use of heavy transformers. Their construction furthermore has rendered their operation extremely slow, uncertain and often unsatisfactory. This is particularly so since the heating of. the rivet or other metal object taking place in a single operation and without any satisfactory means, automatic or otherwise, for regulating the flow of heat current, has often resulted 1n burning the rivets by overheating the same.

By means of my present invention the aforesaid disadvantages of the devices hitherto employed in this art for heating rivets and the like are practically and in a highly eflicient manner substantially entirely overcome, and certain advantages hereinafter more fully pointed out are attained, resulting in economy of current, and a less expensive and within certain limits, automatically accommodates itself to varying sizes or lengths of rivets and does not burn the same, since the heating operation is conducted not in a single powerful stage but in a succession of moderate. heating stages.

Referring to the drawing, there are sho at (a) rivets disposed upon a metal band or other suitable support 1. The rivets (a) are picked up, one at a time, b the person operating the machine and aced 1n the groove (7)) in the band 1. The angle iron 2, which is a continuation of and completes the band 1, is made adjustable with respect to the stationary part of the band 1 by means .of the cleats or eyelets 3, of which two are shown in Figure 2 of the drawing, and the screws 4. By adjusting the angle iron 2 by means of the slots 3' in the cleats or eyelet-s 3 and the screws 4, the band 1 may be adjusted to accommodate rivets of various diameters for which the machine is to be set. I

While various means may be employed for intermittently advancing the rivets, prefer less cumbersome device which, 7

. teeth 17' to employ the means shown comprising a sprocket chain 5.' mounted on the s rockets 6 and 7. Spaced at proper interva along the chain 5 and carried by the same are the links 8. The chain 5 is caused to move, as in the direction shown by the arrow (0), and preferably intermittentl by suitable mechanism, so that a rivet p aced behind one of the links 8 in the groove (7)) is advanced successively into position in front of and between the pairs of upper and lower jaws or electrodes, of which any suitable number may be employed, three such pairs being shown here byway of example and being respectively numbered 9 and 12, 10 and 13, and 11 and 14.

The intermittent movement of {the sprocket chain 5 may be accomplished in the following manner: The sprocket wheel 7 is connected to a shaft 15, which is in turn pinned or otherwise rigidly attached to a ratchet 16, as more clearly shown in Figure 1 of the drawing. Mounted on the same shaft 1.5 there is a cooperating ratchet 17 which has cut in its periphery. Engaging with the teeth 17 on the ratchet 17 are the teeth 18' of a rack 18. Atizhe lower end of the rachet 17 there is mounted a comprestwo ratchets 16 and 17, together with the spring 19, are contained within a housing 21 mounted on the bracket 20, the housing 21 in turn acting as a guide for the rack 18 for which purpose the housing is provided with an extension in the form of a cylindrical hollow member 21.

The shaft carrying the rack 18 is made in twoportions, 18 and 18", which portions are connected by the turnbuckle 22. At the outer end of the portion 18 of the shaft carrying the rack 18 there is mounted a roller 23 mounted in the yoke 24 at the end of section 18 and the rack shaft. The roller 23 bears against the cam 25 mounted on the main cam shaft 82, as more clearly shown in Figure 3 of the drawings. A spring 26 is mounted on the rack shaft on part 18 of the same between the housing 21 and the turnbuckle 22. The spring 26, which is' a compression spring, by its action against that end of the turnbuckle 22 which is adj acent part 18 of the rack shaft, tends to ush the rack towards the cam shaft in the neo- ,tion indicated by the arrow (d) in Figure 1 3 of the drawing.

and pushes the rack periodically in a direc-' tion opposite to the direction indicated by meaeoe the arrow ((1) by means of the engagement .ofthe cam 25 with the roller 23 carried at the lower surface of the ratchet 16, the

ratchet 16 being pinned orotherwise rigidly attached to shaft 1 5, which is in turn rigidly pinned or otherwise attached to the sprocket wheel 7. It will therefore be seen that a complete revolution of the cam 25 causes the rack 18, by reason pf its engagement with the ratchet 17, which is carired by the shaft 15, which also carries the sprocket wheel 7, to advance the chain member 5 one link for each revolution of the ratchets 16 and 17. By these means the rivets in front of the links are advanced one space for each revolution of the ratchets 16 and 17.

Mounted on members 26 and 27, as more clearly shown in Figure l of the drawing, are a plurality 'of transformers, here shown as three in number, and respectively identified by the reference numerals 28, 29 and 30. It will be seen that the number of transformers corresponds to the number of pairs of upper and lower jaws or electrodes 9 and 12, 10 and 13, and 11 and 14. The number of transformers that may be used may be varied within considerable limits, but for the purpose of illustration there are here shown three transformers, since this number is sufficient to exemplify the principle of the present invention. The primary terminals of the transformers are connected to the usual service line supplying alternating current, while one of the legs 31 of the secondary coil of each transformer is connected by means of a cable 34 to the respective upper jaw or electrode 9, 10 or 11. The other leg 37 of each transformer is connected by means of the cable 40 to the respective lower jaw or electrode 12, 13 or 14. Since the lower jaws or electrodes 12, 13 or 14 are preferably all constructed alike, it will be sufiicient to de scribe the construction of a single lower jaw or electrode, such, for example, as the aw or electrode 12. The electrode 12 is mounted on an angle casting 43, as more clearly shown in Figure 1 of the drawing. Yoked around the casting 43 is a lever 46 which is pivoted to the casting 43 by means of a pin 49. ,The main bearing of the lever 46 is on the cylindrical rod or bearing 52, as shown in Figures 1 and 3 of the drawing.-

Springs 53, 54 and 55, as more clearly shown in Figure 1 of the drawings, are provided, these springs bearing against the respective washers 56, 57 and 58. These washers press against shoulders on the connecting rods 59, 60 and 61, which are in turn pivoted in the side plate 62 on the respective pins 63, 64 and 65. The side plate 62 is pivoted to the lever 46 about .the pin 64. The com bined compression force of the springs 53, 54 and 55 is exerted through the side plate 62 on the pivot point 64, which in turn causes the combined compression force of these springs to act upon the lever 46 about the pivot point 52. This action causes the lever 46 to tend to raise the angle iron 43 b means of the connection of the latter with the lever 46 on the pivot 49. The direction of this movement, which is upward, is indicated by the arrow (e).

The central connecting rod 60 hasat the end opposite the pivot point 64 a oke 66 connected at the pivot point 69 wit a bell crank lever 72. The bell crank lever 72 is pivoted on a pivot shaft 75, as more clearly shown in Fi ure 3 ofthe drawing. The free end of the ell crank lever carries a roller 76. This roller is in contact with a cam 79 mounted on the main cam shaft 82. The pivot shaft 75 is mounted in two brackets 83 and 84, as more clearly shown in Figure 3 of the drawings.

At its upper end the angle iron casting 43 is provided with a pivot 85, about which is yoked the lever 86 pivoted about the shaft 87. By means of the levers 46 and 86 pivoted and arranged as described above, it is possible to give each of the lower jaws or electrodes 12, 13 or 14 a substantially rectilinear motion into and out of contact with the lower or unheaded ends of the rivets (a) It- 79, by means of its rotation about the shaft 82 to which it is fixed, acts upon the roller 7 6 carried at one end of the bell crank lever 72 pivoted about shaft and against the action of the springs 53, 54 and 55. The bell crank lever, through the yoke 66 pivoted at its lower end at 69, and by means of the connecting rod 60, tends to compress spring 54 and also, through the connection of the side plate 62 pivoted to lever 46 at 64, tends to compress the springs 53 and 55 which are coiled about the respective connecting rods 59 and 61.

It therefore follows that when the cam 79 is at its highest point, as shown in Figure 1 of the drawing, the springs 53, 54 and 55 will be under maximum compression and the levers 46 and 86 will be in their lowermost position, also as shown in Figure 1 of the drawing.

This position of the lovers 46 and 86 corresponds to the lowermost position of the lower jaws or electrodes 12, 13 and 14. It will, of course, be understood that the object of the lever 86 is to provide proper support for the angle iron casting 43 and to cause the same to rise upward in an are or line firmly and accurately into contact with the lower unheaded ends of the rivets (a). By means of the lever 86 I am enabled to do away with other more complicated steadying and supporting devices for the angle iron castings 43 or their equivalents.

When the cam 79 is in its lowermost position, the bell crank lever 72 is more nearly horizontal than shown in Figure 1 of the drawing, thus causing it through its con nections described above, to permit the springs 53, 54, and 55 to be free to exert tieir combined pressures about the pivot point 64 of the lever 46 to cause the same to be turned about its pivot 52, so that its inner end, pivoted at 49 to the angle iron casting 43, is caused to rise. This rising action of the inner end of the lever 46 causes the angle iron casting 43, steadied and supported by the lever 86, to bring the lower jaws or electrodes 12, 13, and 14, respectively,

carried by the angle iron castings 43, into operative conductive relation to the lower ends of the rivets (a) and at the same time to raise the rivets so that the heads of the rivets come into operative conductive relation with the upper jaws or electrodes 9, 10, and 11, respectively.

When the lower electrodes 12, 13 and 14 have been brought into" contact with the lower ends of the respective rivets (a) and have raised the rivets so that their heads are in contact with the respective upper electrodes 9, 10 and 11, the further rotation of the cam 79 merely causes the cam to swing past the roller until at a certain stage of its revolution it permits the levers 46 and 86 under the action of springs 53, 54 and 55 once more to withdraw the lower electrodes 12, 13 and 14.

Current passes through the rivet by contact of the same with the respective upper and lower electrodes, and current is permitted to pass until one stage of the heating operation, for example the preliminary or initial stage, is completed. Thereupon the lower electrode is withdrawn and the preliminarily heated rivet is passed to the-second set of electrodes and the operation described above repeated and the rivet submitted to a second or intermediate heating stage. The last heating stage takes place at the last set of electrodes to which the rivet is advanced in the manner already described. After leaving the last set of electrodes the heated rivet is carried by its link 8 beyond the electrodes to where the operator may remove the same for use as desired.

It will beapparent that the circuit is closed through each rivet a) by the rivet' being raised mto contact wit the up electrodes by the upward movementof 1; lower electrodes, thus closing the electric circuit through the secondary and causing'the rivet upwardlyand retains the same in raised position fora length of time which will be proportional to the heating requirements of the upper electrode. In the present embodiment shown herein for purposes of illustration, this length of time will be proportional to one dimension of the rivet, for example, proportional to its length. That is, if the rivet is longer, the circuit through it is closed sooner and the heating current accordingly maintained through the rivet a proportionately longer time. Accordingly, the device here shown and described brings about a highly effective and simple automatic adjustment of the heating current in accordance with the demands of the rivet held between a particular pair of electrodesat a particular time.

The cam shaft 82 is mounted in brackets 88 and 89, which brackets are fastened to the two channel iron frames 26 and 27 more clearly shown in Figure 1 of the drawings. The channel iron frames 26 and 27 are in turn connected to another channel iron frame 90 by means of the connecting rods 91.'

There is also provided a bracket 92 supporting an angle iron 93 suitably attached to the bracket 92 by any suitable means, on which angle iron are mounted the upper electrodes 9, 10 and 11. The shafts 52 and 87 are like: wise carried by and pivoted in the bracket 92, which also carries the housing 93, in which the chain sprocket wheels 6 and 7 are mounted. Preferably, the sprocket wheel 6 is mounted on a stud 94 which is adapted to be slidably adjusted within a slot 95 to keep the chain tight A rail 96 may be provide'd about the band 1 to act as a retaining wall for the rivets which are kept on the band. The machine derives its power from any suitablesource not here shown by means of the tight and loose pulley 97 at the end of the cam shaft 82.

The operation of the machine will be clear from the foregoing description. By means of the embodiment of the machine I have described and the process which may be practiced by means of said embodiment of the machine, heating of the rivet takes place in successive stages by successive increments of heat serving to raise the rivet or other metal object to be heated, to the desired temperature. This is accomplished by supplying successive increments of heating current or, in other words, by passing the ourparticular avcaece rent throughthe object to be heated in succes'sive stages, preferabl from a plurality of pairs'or sets of heating electrodes. By these means a plurality of small transformers connected to respective pairs or sets of electrodes may be utillzed in place of the larger and cumbersome transformers hitherto employed. The heating of the rivets or other metal objects taking place in stages, burning of the rivets or other metal objects being heated, and overheating of the same, are substantially avoided. By means of the process and. apparatus described above amuch quicker and more efiicient heating of the rivets or other metal objects may be efi'ected. This is particularly true if a comparatively large number of pairs or sets of electrodes is employed, in which case the heating operation may take place in more than two or three stages, as in' six or eight stages or more. By increasing the number of heating stages, the number of rivets which may be heated in the machine in a unit of time is proportionately increased. It will be noted also that by means of the construction described above automatic adjustment is made for the heating demands of a particular, rivet being heated by any particular set of electrodes at a particular time. Furthermore, this automatic adjustment is accomplished in a very simple and highly ingenious manner and is efi'ective to take care of Variations in the rivets that often occur in practice, or in such cases where it is desired to put through the same machine rivets of difierent sizes to be used for different purposes or in difierent parts of the same structure where the rivets are to be inserted.

It is of course to beunderstood that my invention is not limited to the specific embodiments thereof herein shown and described for pur oses of illustration only, and that other mach practicing the process herein described and claimed, and that a large variety of metal objects other than rivets may be properly heated by the apparatus of the present invention, which may be modified within wide limits while still embodying the substance of the present invention.

What I claim is:

1. In an electric rivet heaterfa plurality of pairs of heating electrodes, and means for bringing a rivet into operative conductive relation to successive pairs of heating electrodes to thereby heat such rivet in successive stages.

2. In an electric heater for metal objects, a, plurality of sets of heating electrodes, and

ines may be constructed for means for bringing each of a series of metal means for bringing a metal object to be,

heated into operative conductive relation to successive sets of heating electrodes to thereby heat said object'in successive stages by successwe increments of heating current and means associated with at least one 0% said sets of electrodes for varying the heating current supplied at said set of electrodes in accordance with the heating current demands of the particular metal object in contact with said set of electrodes at a particular time.

4:. In an electric heater for metal objects, plurality of sets of heating electrodes, means for bringing each of a series of metal objects to be heated into operative conductive relation to successive sets of heating electrodes to thereby heat each of said objects in successive stages by successive applications of heating current, and means associated with at least one of said sets of electrodes for varying the heating current sup plied at said set of electrodes in accordance With the heating current demands of the August, 1921.

FRANK P. KOBERT. 

